Trunk Light Problem

[alchemist]

My 1967 230SL trunk light is not working. I checked the bulb which is good. I took the switch out and cleaned all the connections. I checked if there is a power at the plug and found no voltage coming to it. It has 2 connectors, brown for ground and light blue wire. I checked the fuse box and found that all fuses are OK.I wonder if any one faced such a problem and found the source of in-connectivity?

[kampala]

Have you checked to see if the trunk light works while the headlights are turned on? 

[lreppond]

I had a similar issue and located a break in the wire near the trunk lid hinge (on left side as you face the trunk).  I replaced all the wiring and no longer have an issue. 

In later models, the trunk light comes on even if the headlights are off.  As Kampala has pointed out, with a 230 you’ll need to have your headlight switch on for the trunk light to work.  You might want to check that first.  Could be that nothing is wrong.   

[Jonny B]

As an additional note, the headlights need to be on for the light in the trunk of a 250 SL to light, at least through VIN's ending 2979

[JamesL]

Same as Len - my cable was damaged around the hinge of the trunk
I replaced my bulb with a stickon LED panel that actually provides illumination (panel is powered via a bulb fitment)

[Paul99]

with my 1966 230, the lights need to be on for the boot (trunk) light to work.

[lpeterssen]

Dear friends

The cable that feeds rear trunk courtesy light belongs to circuit 1.  It is always energized. If you have no power at the accesory, then for sure the cable is melted or cut somewhere across its route.

Open 12 pin connector at driver side footwell and look for a red/yellow/white line and measure voltage there at the terminal.

If you have power there, then you need to replace the whole cable from one end to the other. Not recommended to have splices on that line in particular.

Best regards
Lp
Www.wiredoktor.com

[rwmastel]

The cable that feeds rear trunk courtesy light belongs to circuit 1.  It is always energized.

Many of us disagree.  Perhaps you are referencing a 280SL diagram?  OP has a 230SL.

I actually looked in my owners manual, an English/German edition numbered 113 584 05 96.  I can't find any mention of the trunk light.  Not in the description of the light switch on the dash or in the electrical diagram (included in the book).

Maybe this helps?  https://www.sl113.org/wiki/Electrical/Trunklights

[BobH]

From what i understand, the trunk light was an option on early cars, and depending on the date of production, could have been powered from the rear lights, so only illuminated when the rear lights were on, or could have been powered directly from fuse *1, in which case would illuminate independently from the rear lights

I would trace the wires and see where they route and repair or replace as necessary

[alchemist]

I actually got power of 12 V at the plug where the switch plugs in, only when the head lights are on. So, my wires are ok, however the switch is the problem. I used ohmmeter to check connectivity inside the switch, that required cleaning up all connectors using a small file. The ground tested OK after cleaning, but, the power connecter is not. When you look how this switch is made, there is no way to insert any tool to clean the power connector.
Is any one has experience of repairing the truck switch? The only way I can suggest is to clean the metal connectors chemically, perhaps, by using hydrochloric acid on the dilute side.

[Pawel66]

I think everything is all right there. I suppose your trunk light may also work when parking lights are on, not only headlights. I think this is how it is wired.

[rwmastel]

alchemist,

So, you're saying that when the headlight switch (at the dashboard) on, you get 12v at the trunk switch, but not through the switch to the bulb socket??

(As many have said, we believe the trunk light should only be powered when headlights are on.)

[BobH]

I actually got power of 12 V at the plug where the switch plugs in, only when the head lights are on. So, my wires are ok, however the switch is the problem. I used ohmmeter to check connectivity inside the switch, that required cleaning up all connectors using a small file. The ground tested OK after cleaning, but, the power connecter is not. When you look how this switch is made, there is no way to insert any tool to clean the power connector.
Is any one has experience of repairing the truck switch? The only way I can suggest is to clean the metal connectors chemically, perhaps, by using hydrochloric acid on the dilute side.

There are many electrical contact cleaners available, if you can actually get the cleaner onto the contacts, it might be worth a try

Otherwise, i found these, you'll need to check if they are the same as your switch

https://www.ebay.co.uk/itm/305274790819?chn=ps&norover=1&mkevt=1&mkrid=710-153316-527457-8&mkcid=2&itemid=305274790819&targetid=4584757337008488&device=c&mktype=&googleloc=&poi=&campaignid=431353847&mkgroupid=1298523655396099&rlsatarget=pla-4584757337008488&abcId=9301942&merchantid=87779&msclkid=bb9926e582e4179835f6433bb6c741f9

Or a cheaper switch here

https://www.2040-parts.com/trunk-light-switch-for-mercedes-230sl-250sl-w113-280se-w108-coupe-w111-i2252439/

[alchemist]

Thanks to all contributor to my problem. I was able to fix the switch by using hydrochloric acid (stomach acid). I used 2% of this acid sold at your hardware store under different name. The acid reacted with the metal and removed the oxidation at the contact points. The + terminal was the hardest to clean, this is why I used the acid. If you planning to use the same method, wear goggles and mask and dip the switch in the acid for a short time, perhaps, 5-10 minutes (do not use your fingers). You will see fumes started to form. Do not leave it in the acid for long, it will dissolve all the connectors. The light is only works when the headlights are on. I tried another acid by using white vinegar which is a weak acetic acid. It worked to some extent, but not to the full extent.